164 A. W. jPeirce — Existence of Selenium Monoxide. 



aromatic series by means of nitric acid, and filtering on glass 

 wool. The product when dried quickly at 100° gave results in 

 accord with his theory of the constitution of the compounds, 

 counting the selenium dried at 100° as existing in elementary 

 form. Thus : 



I. IL III. 



Se found 0*0347 0'0680 00406 



Se by theory 0*0349 0*0678 0*0414 



0*0002— 0*0002+ 0*0008 — 



In other analyses of the same compounds, in which the 

 selenium was dried at 180° instead of at 100°, the weight of 

 the selenium was so much greater as to suggest the idea that 

 the element had oxidized to the condition of the monoxide. 



Thus : 



I. II. III. IV. 



SeO (?) found-.. 0*0301 0*0525 0*0523 0*0517 

 SeO by theory... 0*0301 0*0517 0*0504 0*0498 



0-0000 0*0008+ 0*0019+ 0-0019 + 



Had Ohabrie actually found that the same identical selenium 

 determined by drying to a constant weight at 100°, did actually 

 increase in weight at 180° to a constant amount corresponding 

 exactly to what the weight should be were the monoxide formed, 

 the evidence of such oxidation would be good. What Chabrie 

 did, however, was to show that when the selenium from one 

 sample of his compound was dried at 100° and regarded as 

 elementary selenium, the amount of it found corresponded to 

 his theory of the composition of his compound ; while to har- 

 monize the results of analysis with the demands of the theory, 

 when the selenium from another sample of the same prepara- 

 tion was heated to 180° it became necessary to assume that the 

 selenium had been oxidized to the condition of the monoxide. 

 Moreover, it has been shown very recently by Krafft and 

 Kaschau* that the composition and constitution given by 

 Chabrie to some, at least, of his organic compounds of selenium 

 cannot be sustained. It has seemed to be desirable, therefore, 

 to put the question of the oxidation of selenium at 180° to the 

 direct test. 



I have dried selenium to a constant weight at 100° C. 

 and then have heated it to 180° C. for various periods of time, 

 and in no single case have I observed the slightest increase in 

 weight. In the following table are the results of these experi- 

 ments. In every case the selenium was taken originally as the 



* Ber. d. d. Chem. Gesell., xxix, 428. 



